Expanding anchor and plug with an exhaust passage



J. H. sHlELDs 2,963,935

AUST PASSAGE Dec. 13, 1960 EXPANDING ANCHOR AND PLUG WTH AN EXH Filed Aug. 10, 1956 5 Sheets-SheeI 1 fifa/'nega @Www C@ J. H. SHIELDS Dec. 13, 1960 EXPANDING ANCHOR AND PLUG WITH AN EXHAUST PASSAGE Filed Aug. l0, 1956 5 Sheets-Sheet 2 mm I Inv efyzorI Joseph cSn'e/d ZZlC Dec. 13, 1960 J. H. SHIELDs 2,963,935

EXPANDING ANCHOR AND PLUG WITH AN EXHAUST PASSAGE Filed Aug. l0, 1956 5 Sheets-Sheet 3 42 Inventor Joseph. 'f. Shields United States Patent O EXPANDING ANCHOR AND PLUG WITH AN EXHAUST PASSAGE Joseph H. Shields, Wilmette, Ill., assignor to John H. Van Moss, Jr., Chicago, Ill.

Filed Aug. 10, 1956, Ser. No. 603,448 8 Claims. (Cl. 85-2.4)

This invention relates to anchoring devices of a kind utilized in fastening anchor bolts in concrete, and particularly the invention relates to such devices having an anchoring shell that serves as a drill for drilling the necessary anchoring hole in the concrete. This is a continuation-in-part of Serial No. 438,748, filed June 23, 1954, and now abandoned.

While shell drill anchoring devices adapted to be inserted in concrete by drilling of anchoring holes in such concrete are relatively old, such devices have long been considered to be inefficient insofar as resistance to certain kinds of loosening or removing forces may be concerned. In particular, the shell drill type of anchoring devices heretofore used have afforded relatively ineiiicient anchoring forces against rotative or torsional forces that might be applied to the anchors, and in addition to this, the resistance of such devices to endwise withdrawing movement of the anchoring shell has not been particularly high. Because of this, it has been necessary to utilize relatively large anchoring devices in many instances where, insofar as the strength of the anchoring bolts might be concerned, rthe use of a smaller anchoring device would be indicated. In view of the foregoing, it is an important object of the present invention to improve the anchoring action that may be attained in anchoring devices of the aforesaid character, and particularly it is an object to materially improve the action of such anchoring devices insofar as endwise removal and torsional displacement thereof may be concerned. Further and related objects of the present invention are to enable the foregoing objects to be accomplished by a structure that is simple in character and economical insofar as manufacturing costs are concerned, and to adapt such anchoring devices for the application of anchoring forces by the usual type of air operated impact or driving tools, and to enable a shell drill to be operated in a novel way by an `adapter having portions complementary to portions of the shell.

`Other' and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustration, show preferred embodiments of the present invention and the principles thereof and what I now consider to be Ithe best mode in which I have contemplated applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the purview of the appended claims.

In the drawings:

Fig. 1 is -a perspective view of a shell drill `anchoring device embodying the invention;

Fig. 2 is an end view of the shell drill anchoring device showing the tooth structure thereof;

Fig. 3 is a side elevational view of one form of expanding plug that may be utilized with the shell drill of Figs. l and 2;

Fig. 4 is an end View of the large end of the plug shown in Fig. 3;

Fig. 5 is a sectional view illustrating the shell drill of Fig. 1 as it is used in forming anchoring holes in material such as concrete;

Fig. 6 is a view similar to Fig. 5 showing tht shell drill after the expanding plug has been put in place in the drilled hole and after the shell drill has been driven through a portion of its expanding or anchoring movement;

Fig. 7 is an enlarged view similar to Fig. 6 and illustrating the lower end of the shell drill after further expansion of the inner end of the shell;

Fig. 8 is a side elevational view taken partially in longitudinal section yand illustrating another form of shell drillv embodying the features of the invention;

Fig. 9 is a side elevational view of an expanding plug embodying the features of the invention and adapted for cooperation with the shell drill of Fig. 8;

Fig. 10 is a view somewhat like Fig. 7 and showing the shell of Fig. 8 in its cooperating and substantially anchored relationship with respect to the plug of Fig. 9;

Fig. 11 is a side elevational View of an alternative form of expanding plug adapted for use with the shell drill of Fig. 1 under the present invention;

Fig. 12 is a top plan view of the plug of Fig. 11;

Fig. 13 is a bottom plan view of the plug of Fig. 13;

Fig. 14 is an exploded view of a shell drill assembly, including an adapter;

Fig. 15 is a sectional view of the shell and adapter shown in Fig. 14;

Fig. 16 is a sectional view of the shell;

Fig. 17 is a sectional view taken in the line 17-17 of Fig. 16; and

Fig. 18 is a View at the drill end of the shell.

For purposes of disclosure, the invention is illustrated in Figs. 1 to 7 of the drawings as embodied in an anchoring device of the self drilling type that comprises a generally cylindrical drill shell 20 and `a tapered anchoring plug 21. The drill shell 20 is formed from a relatively hard metal such as steel, and comprises an outer end or head portion 20H and a relatively long inner drill end 20D. In the form illustrated, the internal cylindrical surface of the head 20H is internally screw threaded as. at 20T to receive an anchoring bolt after the anchoring device has been anchored in position in a structure such as a concrete road, wall, iloor F or the like. At its inner or leading end, the drill portion of the anchoring shell 2i) is provided with a plurality of drill teeth 120, and the Wall portion of the anchoring device 2i) between the head 20H and the predetermined cutting diameter of the teeth is relieved or reduced somewhat in diameter, as indicated at 20'R, so that the drill teeth project slightly outwardly with respect to the surface 2BR, and will drill a hole H in the wall or lloor F that is somewhat larger in diameter than the diameter of the reduced portion 201K. This affords an annular clearance space through which the dust produced in the drilling operation may be ejected from the hole H as will be described hereinafter.

The drilling port-ion 20D of the anchoring drill sleeve 20 has a plurality of longitudinally extending weakened lines formed thereon so that when the drill end of the sleeve 20 is expanded, the drill portion 20D may be fractured or split along these lines, thus to form separated longitudinal sections of the drilling portion 20D which may then be forced rmly into contact with the Walls of the hole H. In the form of the invention illustrated in Figs. 1 to 7 of the drawings, such weakened lines are afforded in the portion 20H of the shell 20 by a plurality of longitudinally extending grooves 20G that are formed in the external cylindrical surface of the shell 20 `throughout substantially the entire length of the drill portion 20D.

A shell drill 20 of the form that is thus afforded may be used in a conventional manner as a drill to form the hole H by attaching the same to the operating head of Patented Dec. 13, 196i)` an air operated hammer or sinker that is of conventional form. Such a sinker operates with a percussive action that in each cycle imparts a longitudinal blow to the shell Vdrill 20-as well as `a minor component of rotative .force so that the drillingaction that is attained is comparable t'ofthat obtained through the use of a star drill. In such sinkers, it is customary to exhaust air `from the operating cylinder'thereof longitudinally and into the hole that is being drilled, and such exhaust air is under high pressure and passes downwardly lthrough the drill shell 20. This air escapes around and between the teeth 120 and passes outwardly in thefannular exhaust space that is aiorde'd between surface 20R and the Wall of the hole H, and the exhaust of such kair serves to blow the dust and refuse out of the hole H. Y After the hole H has been drilled to the desired depth, as for example to the depth illustrated in Fig. 5, the shell drill l20 is withdrawn, and tapered expanding plug 21 is put in place in the hole H with the small end of the plug facing koutwardly of the hole. The shell drill 20 is then inserted into the hole soV that its leadingor toothed end edge surrounds thek small end of the plug 21, and under and in accordance with the present invention, the tapered expanding plug 21 vis so formed as to attain a novel expanding action on and with respect to the drill 'end of fthe shell drill20, and this action is `such that the anchoring strength 'of the device isV exceptionally high, particularly insofar as rotative forces and endwise withdrawing forces may be concerned. p, v

4In attaining ythe improved anchoring action ,under the present invention, the tapered expanding plug 21 is formed with a varying 'taper so that a relatively slight taper is alforded throughout themaiorY portion ofthe lengthV of, the 'plug 21, while a greatly increased taper is afforded near the Y'base of the plug. Thus, as will be evident particularly in Figs. 3 and 6 ofthe drawings, the plug 21 has a relatively Ylong forward tapered portion in which the taper is relatively small, and near the base of the plug the taper 21S merges with a portion 21L Vthat has a greater taper. The lforward portion of the plug 21 is also provided with one or more annular grooves 21G that atford 'sharp vannular teeth 21T facing toward the base end of the plug and which serve to afford an increased locking action between the anchrrinrgvshell 20 and the plug 21. The vplug 21 has a longitudinal'passage or bore 21B formed so as to extend vfrom endqto end thereof on its central axis, and a cross slot 21C is formed in the head vor large end of the plug 21 so that the exhaust air lfrom the sinker may pass downwardly through therbore 21B and then laterally through the cross -slot 21C, so `that during the driving operation that is required for expanding the shell drill 20, the ,additional dust and refuse produced as the forward or toothed end of the shell is expanded may be discharged from the hole H by the exhaust air.

The proportioning of the shell drill 20 and the expanding plug 21 may, of course, be varied to aconsiderable extent, but I prefer to so yproportion these elementsvthat the plug 21 is engaged by the inner surfaces of the teeth 120 at substantially the point where the rst one of the grooves 21G is located, and hence, during further inward driving movement'of the shell'drill 21, the end portion of the shell drill will be continuouslyvexpande'd and a further slight drilling operation willbe accomplished by then teeth 120 to somewhat enlarge the lower portion of the hole H. In the course of such Vdriving of the shell drill, the portion 20D thereof will be fractured along the lines dened by the grooves 20G to form a plurality of arms that may bend outwardly as the driving operation progresses. When the tooth end'of the drill 20 engages the larger taper 21L, the ends of the drill will be directed outwardly at a relatively steep angle, as Aillus- Ytrated in Fig. 7 of the drawings, and in this further driving movement, the drilling action will, of course, be increased and the ends ofthe armsthat have been formed 4 by splitting of the drill end 20D along the lines 20G will be projected substantially beyond the radial limits of the outer portion of the hole H thus to etfectually anchor the drill shell 20 against. endwise withdrawal. In theevent that the final driving `l"forces` are app/lied tothe drill shell 20 without the lptativeY component of force hereinabove described, the Yends of the separated arms of thedrillportion 20D will effect an Vunusually eiiicient rotative interlock with the material of the wall or door F.

It will be recognized that the outside surfaces of the shell drill 20 will be engaged with the walls of the holes H throughout a substantial portion of the length or the depth of thehole H, and by reason of the double taper of the expanding plug 21, this engagement is even more effective at the inner end of the shell 20, where the distance between the outer surface of the iloor or wall F is greatest so as to utilize the strength of the material of the wall or iloor to obtain maximum anchoring strength.

In Figs. 8 and 9 of the drawings, therinvention is illustrated in a modied embodiment that comprises a shell drill 220 and a 'doubleutapered expanding plug 221. In most respects, the shell drill 220 is identical with vthe shell drill 20, but in this instance, the reduced outer surface 220K is smooth or unbroken, and the weakened longitudinal lines are provided by affording the internal surfaces of the shell 220m a non-circular or non-cylindrical cross sectional form. Thus as shown in Fig. 8, such weakened lines are aiforded by longitudinal grooves 220G that are formed in the inner surface of the drill end of the shell drill, as willbe `evident in Fig. 8 of the drawings, and such grooves 220G serve additionally as air passages as will appear hereinafter. A cross slot 221C is also afforded across the lowerend of the plug 221 so as to aid in preventing accumulationrof dust and refuse in the bottom of the hole in which the plug 221 is used. y f

`With the shell drill thus formed, the double taper plug 221 is identical with the plug 21 except that Ythe plug is solid or, in other words, does not have longitudinal and Ytransverse openings or passages such as the passages 21B and 21C hereinabove described. With this arrangement, the shell drill 2207is operated as a drill in the same manner as hereinabove described, but when the drilling operation has been completed and the plug 221 is put in place, the downward passage of the exhaust air from the sinker is taken care of by the longitudinal internal grooves 220 G that are'formed in the shell drill 220. In other respects, this embodiment of the invention is identical in its operation with the structure illustrated in Figs. 1 to 7.

The expanding plug may also have the requisite longitudinal air passage means aiforded in the manner illustrated in Figs. 1l to 13, wherein a double tapered plug 321 is formed that is solid insofar as 'its internal form may be concerned, and a plurality of longitudinally extending grooves 321G areprovided along the outer surfaces of the plug 321. This plug 321 may be utilized as the expanding plugfor a shell -drill such as that shown in Figs. 1 and 2, and in theexpanding operation, the grooves 321G afford an inward or downward passage for the exhaust air so that this exhaust air may function to discharge the dust and refuse from the hole H during the expanding or anchoring operation. A cross slot 321C is also provided in the large end of the plug 321 for the same purpose as the slot 221C.

From the foregoing description, it will be apparent that the present inventionaiords an anchoring device wherein the anchoring actionis superior'tothe'anchoring action heretofore attained, "and the devices herein disclosed under the present invention are of sucha character'that the final driving or anchoring operation may be performed by a percussive sinker without altering the advantageous operation of 'such a tool.

'It is important top'oint out'thattheY final driving or anchoring operation is greatly enhanced by provision of the reduced diameter of the shell as at 20R and 220R. Thus, as was mentioned, there is afforded in the present instance a novel kind of expansion at the drill end of the shell centered on the expanded plug, and this is attained through the sharp taper as 21L and 221L of the plug. A great deal of friction and resistive binding would normally be expected during this operation, but by reducing the diameter of the shell in the manner mentioned full expansion is allowed at the bottom or sunk portion of the shell since there is space between the hole H and the sides of the shell Where the aforesaid reduction in shell diameter is afforded. In other words, gradual and completely effective expansion at the bottom of the shell is allowed to occur, inasmuch as the entire reduced diameter portion of the shell has room to expand within the hole H. This condition is apparent in Figs. 6 and 10 wherein spacing yet exists between the hole and the portion of the shell just below the head thereof even though expansion of the shell has already been attained.

In Figs. 14 to 18, the present invention has been further modified to accommodate in a novel way a highly advantageous kind of drive adapter. The shell 420, Fig. 14, is similar to the shell 220 described above, including drill teeth 420DT at the lower end of the intermediate drill portion 420D. The head 420H of the shell in this instance is modified as will be explained to cooperate with a complementary drive adapter 400, and the drill portion 420D below the head 420H is reduced in diameter at 420K for the purposes mentioned above.

The plug 421 is solid and includes an upper tapered portion 421S and a base that has a greater taper imparted thereto at 421L. Thus, the plug 421 is similar to the plug 321 described above except that grooves as 321G are not employed, and the base 421L is slotted at 421C for the purpose described above.

The shell 420, like the shell 220, is weakened internally by circumferentially spaced and axially extended grooves 420G which, as shown in Fig. 18, are triangular in shape, having vertical side walls that converge from the inner wall of the shell toward the outer wall of the shell. To facilitate initial and then easily continued fracture or splitting of the shell during the final anchoring operation, the grooves 420G are tapered from a thick upper end 420GT downwardly to a thin or weakened lower end 420GN as shown in Fig. 16.

The shell 420 is threaded internally at 420T, these threads being provided in the head portion 420H. The upper end of the head 420H is defined by an annular thrust bearing seat or surface 430, and an internal annular centering seat or shoulder 431, which is of less diameter than the bearing seat 430 and is spaced below the bearing seat. The threads 420T terminate at another internal shoulder 432 which is of smaller diameter than the shoulder 431, and the shoulder 432 is spaced above a pair of drive lugs 4201.41 and 420L-2, Fig. 17, formed in diametrically opposite poistions on the internal wall of the drill portion 420D of the shell.

The shell 420 is to be driven by an adapter 400, Figs. 14 and 15 which is adapted to impart percussive action to the shell drill 420 during formation or drilling of a hole as H, Fig. 6, The adapter 400 is also adapted to drive the shell 420 during the shell anchoring operation at the time when the plug 421 has been placed in the hole drilled by the shell. Thus, the adapter 400 includes a head 400H which is threaded internally at 401 enabling the adapter 400 to be operatively mounted on a conventional type of air driven tool. The lower end of the head 400H of the adapter is dened by an annular shoulder 403 whichV affords a collar 404 of reduced diameter in comparison to the head 400H. The collar 404 is further reduced to afford another shoulder 405, and depending from the shoulder 405 is a stem or shank 40S of reduced diameter in comparison to the collar 404. .As-best shown in Fig 15, the adapter 400 is this bore and the internal bore of the shell so as tol sweep dust or like debris from the hole being drilled by the drill shell.

The lower end of the adapter shank 408 is provided with a pair of bayonet locking slots 415, Pig. 14. Two such slots 415-1 and 415-2 are afforded as shown in Fig. 15 in diametrically opposite positions at the lower end of the shank 408 of the adapter 400. The shank portion 40S and the collar 404 of the adapter are complementary to related parts of the shell 420 so that the adapter 400 can be inserted into the head 420H of the shell with the shoulders 403 and 405 of the adapter re-` posing on the thrust bearing face 430 and the center# ing shoulder 431, respectively, of the shell. As will be observed in Fig. l5, the dimensioning of the parts is such that the outer wall of the shank 408 of the adapter in the intermediate portion thereof is spaced inwardly of the threaded portion 420T of the drill shell 420, thereby preventing damage to the threads of the drill shell which, it will be recalled, serve to anchor a bolt after the drill shell has been expanded within a drilled hole as H. It will be further observed that the shank of the adapter at the lower end portion extends past the shoulder 432 of the drill shell, and this portion of the adapter ap` proximates the diameter of the bore 420B, l1Eig. l5, of the drill shell, and in this manner the adapter is accurately centered in and in circumferential bearing engagement with the drill shell at the aforesaid shoulder portions and the portion of the adapter shank extended beyond the drill shell shoulder 432.

When the adapter has thus been mounted in the drill shell, this is accomplished by so aligning the adapter that the open ends of the bayonet slots 415 are aligned with the lugs 420L-1 and 4201,-2. Then, by turning the adapter in the proper direction, the lugs 420L-1 and 426L-2 repose in the dead end portions of the bayonet slots. llt will be appreciated that impacts delivered to the shell 420 through the adapter 400 have a rotary component, and this component will be of such direction as to tend to tighten the bayonet slots of the adapter on the lugs of the shell, and such action occurs without damage to the threads 420T of the drill shell.

While I have illustrated the preferred embodiments of my invention, it is to be understood that these are capable of variation and modioation, yand I therefore do not wish to be limited to the precise details set forth, but desire to avail myself of such changes and alterations as fall within the purview of the following claims.

I claim:

l. In a shell drill anchoring device, a drill shell having a longitudinally externally grooved expansible cutting end terminating in drilling teeth capable of cutting concrete yand having a predetermined cutting diameter, said shell member having a head portion opposite the drilling end and an intermediate portion with a reduced diameter in comparison to said head portion and said cutting diameter, said intermediate portion extending from the head to the drilling end and the diameter thereof being reduced for the full 'length thereof, yand a tapered expanding plug insertable into the bottom of a hole to extend into and fracture and expand the cutting end of the shell upon inward driving of the shell, said plug having a longitudinal central passage from end to end and an intersecting transverse slot across its inner end through which exhaust air from a pneumatic driving tool may pass inwardly of such :a hole toward the bottom of the hole and then out,- wardly of the hole about the expanded shel'l.

2. A tapered expanding plug insertable into the bottom of a hole to extend into and fracture and expand the cutting end of an vanchoring drill shell upon inward driving of the shell, said plug having a gradual frustoconical taper adjacent its outer end and a greater irustoconical taper adjacent its inner end, Aand said plug having a transverse slot across its inner end through which exhaust air from a pneumatic driving tool may lpass outwardly of the hole about an expanded shell.

V3. YIn an anchoring device, ya hollow tubular shell member having an internal surface conforming to Va substantially constant diameter for a substantial portion of its length land an externally tapered expansion plug member, said shell member having a head at one end of predetermined outside diameter and which head is internally threaded, said shell member having a toothed drilling end of predetermined cutting diameter approximately the same diameter as the outside diameter of said head and the external surface of said shell member between said head and of said toothed end being of uniform reduced diameter for substantially the full length thereof, oneof said surfaces of said shell member being weakened by longitudinal grooves, said tapered expansion plug member being adapted to be disposed in a previously drilled hole ahead of the shell member to fracture and expand the Vshell upon inward driving of the shell member, Vsaid plug member having a gradual frusto-conical taper extending from its outer end for asubstanti-al distance and having an increased frusto-conical taper adjacent the other end of the plug member, and said plug member having a transverse slot in the face of said other end.

4. In fan anchoring device, a hollow tubular shell member having an internal surface conforming to a substantially constant diameter for a substantial portion of its length, and a tapered expansion plug member, said shell member having a toothed dri-llingend capable of cutting concrete and having a predetermined cutting diameter, said shell member having a head portion opposite the drilling end and lan intermediate portion with a reduced diameter in comparison to said head portion and said cutting diameter, said intermediate portion extending from therhead to the drilling end and the diameter thereof being reduced for the full length thereof, said tapered expan sion plug member being adapted to be disposed in a previously drilled hole `ahead of the shell member to expand the shell upon inward driving of the shell member, and said plug member having a gradual frusto-conical taper extending from its outer end for a substantial distance and having an increased frusto-conical taper adjacent'the other end of the plug member, one of said members having passages through which exhaust air from a driving tool'rnay pass through said shell member inwardly toward the bottom of the hole for discharge about inner portions of the shell member and outward discharge about the outside of the shell member, and the face of said other end of the plug member having a transverse slot therein.

5. In an anchoring device, a tubular shell having drilling teeth capable of cutting concrete formed thereon at one end and having internal screw threads formed in its inner cylindrical surface adjacent the other end, said drilling teeth having a predetermined cutting diameter, said shell having a head with a diameter approximately equal to that of said cutting diameter, said shell having the diameter of its external cylindrical surface reduced uniformly and substantially for the full length thereof between said head and said drilling teeth, said shell having a plurality of laterally spaced longitudinal grooves formed in the inner one of its cylindrical surfaces to enable subsequent longitudinal fracture of the shell along such grooves in the course of expansion of the drilling end of the shell and to allow passage of exhaust air therealong, and a solid tapered `expansion plug adapted to be disposed in a previously drilled hole ahead of the shell to fracture and expand the shell upon inward driving of the shell, .saidplug having a gradual truste-conical taper extending 4from its outer end for a substantial distance and having an increased frusto-conical taper adjacent the other end of the Iplug, and'said plug having flat end faces with the face at the increased taper end provided with a transverse slot. Y `Y'6. In an anchoring device, a tubular shell member and a tapered solid expansion plug member, `said -shell member having a toothed drilling end capable of cutting concrete and having -a predetermined cutting diameter, said shell kmember having a head portion Vopposite the drilling end yand an intermediate portion with a reduced diameter in comparison to said head portion and said cutting diameter, said intermediate portion extending from thefhead to the drilling yend and the diameter thereof being reduced for the full length thereof, said tapered expansion plug member -being adapted to be `disposed in apreviously drilled hole `ahead of kthe shell member to fracture and expand the shell upon inward driving of the shell member, and said plug member having a gradual frusto-conical taper extending from its outer end for a substantial distance and having .an increased frusta-conical taper Vadjacent `the other end of the plug member, said shell member having a plurality of longitudinal grooves formed in'its inner surface for fracture upon expansion of said shell member and through which exhaust air from -a driving Ytool may pass Vthrough said ;shell member inwardly toward the bottoni-.of -the Vhole for discharge about inner portions v4,of Ythe shell member and outward discharge yabout the outside of the shell-member, and `said plug having flat end lfaces with the face at the increased taper Vend provided with a transverse slot.

7. Yln an anchoring device, a tubular shell member having =a bore formed therein, a tapered expansion plug, an adapter insertable in the shell fordriving the shell and having iirst and second annular shoulders, said shell member having a thrust bearing surrace at one end complementary to said iirst annular shoulder and an annular centering seat within 'the shell borecomplementary to said second annular shoulder, said shell member having a toothed drilling end, lugs within the bore of the shell member, internal threads in the shell bore between said lugs and said centering seat, said adapter having a shank with slots therein `at the end extended beyond said second annular shoulder for engaging said lugs and Vremovably coupling the shell to the adapter, said shank being insertable in the shell bore and being'of less diameter than the threaded portion of the shell member, said tapered expansion plug member being adapted to be disposed in a previously drilled hole ahead of the shell member to expand the shell upon inward driving' of the shell member, and said plug member having a gradual taper extending from its outer end 'for a substantial distance and having an increased taper `'adjacent the other end.

8. VAn anchoring device according to claim 7 wherein the diameter of the shell vbore adjacent Vsaid lugs is less .than the diameter of said'threaded portion, and wherein the portion of the adapter shankhaving said slots is of such diameter as to be in bearing engagement therewith.

References Cited in the tile of this patent UNITED STATES PATENTS 609,107 Leyner Aug. 16, 1898 801,480 Shaw Oct. 10, 1905 1,137,443 Ackerman Apr. 27, 1915 1,251,566 Pigott Jan. 1, 1918 1,398,985 Wadley Dec. 6, 1921 1,602,498 McCanna Oct. 12, 1926 1,621,598 Phillips Mal'. 22, 1927 1,733,392 Barra Oct. 29, 1929 1,762,349 Phillips June 10, 1930 1,950,513 Pope L Mar. 13, 1934 1,953,172 Griffiths Apr. 3, 1934 1,996,121 Phillips Apr. 2, 1935 2,302,590 Waite Nov. 17, 1942 FOREIGN 'PATENTS V596,275 Great Britain Dec. 31, 1947 1,010,775 France Mar.26, 1,952 

